Strut lathe



Il.. WHHPFLE. Smm MTBE.

wpucm'mn mw Ausns, 1919.

mme@ Non 79 9 4 SHEETSSHEET h L. B. WHIPPLE.

STRUT LATHE.

APPLICATION FILED Amm. I9I9.

Patented Nov. 7, 1922.

4 SHEETS-SHEET 2.

L. B. WH'IPPLE.

STRUT LATHE. l APPLICATION FILED Aus.4. 1919! 1,434,51 6, Patented Nov. 7, 1922.

4 SHEETS-SHEET 3.

Figa

L. B. WHIPPLE.

STRUT LATHE.

APPLICATION FILED Auw. 1919.

34,434@ l )Patented Nov. 7, 1922,`

4 SHEETS-SHEET 4.

Patented Nov. 7, i922.

`iisurini stares .in Se (im lll LELAND B. W'HIPPQE OP ROCHESTER. NEVI ASSEGNO@ l'Z-TlldPRE DOUBLE PIVOT LAST COMPANY, OF AUBURN, MAINE, ,A CQRPQRQEIN 0F MANE.

s'rnufr narnia. j

Application led `.thigust 4, 19719. SeralNo. Bl

To all 'who-m t 'may concern.'

Be it known that I, LELAND B. Wrrirrnn, a citizen oil the United States, residing at Rochester, in the county of Monroe and State of New York, have invented certain Improvements in Strut Lathes7 of which the following description, in connection withv the accompanying drawings, is a specilication, like reference characters on'thedrawings indicating like parts in the several figures.

This invention relates to the copy-turning of irregular objects, and is herein disclosed for illustrative purposes as embodied in a lathe especially designed for making airplane struts. An airplane strut is a wooden member7 from two to ten feet long, of elongated ovoid 'cross-section, the sizek varying ornot, as desired.. throughout the length. Great diiliculty has been experienced in -forming these object-s in copying' lathe due to their' great length, the consequent massiveness of the machinery necessary to handle them, and the jar resulting from the reversal ofimovement of so much material in movement of the amplitude required by the elongated cross-section.

.lt has been found also that two operations are advisable in forming these objectsq since vthe lirst or ordinary tui-nii operationleaves the strut with a shallow helical groove upon in which must be smoothed down. This smoothingoperation is preferably done in a similar lathe wherein all the above described difliculties are met with, together with the additional one that the abra-sive belt used tends to set the long strut in violent vibration as a violin bow does a string.

It is the object of the present inventionto remove these difliculties among others, and to provide a machine which will produce accurate work rapidl7 and economically.

An important feat-ure of the invention resides in a novel organization, including an oscillating' frame comprisino` a circular tube carrying the model and work head and tail stocks. This construction minimizes? the moment of inertia of the oscillating frame, and makes its reversal of movement easy and smooth as compared with other heretofore known types. o

Another feature of the invention resides in a cradle for supporting the strut against lateral vibration. Preferably this cradle. comprisesa member encircling the strut, rotating with it7 and supporting `it on all sides.

in the illustrated machine this member carries resilient fingerspressing againstI the sides of the strut. f

VAnother feature of the kinvention coinprised in gearing for varying the rotational speed of the work during each revolution.

lhis enables the flat and the sharply curved sides of the work which are, respectively, near to and far from the anis of revolution, to be treated at differentangular speeds, so that the surface speeds be cqualized. A large part of the j ar can also be eliminated bythis construction. f Another important feature of the invention resides in a pair of substantially fiat guides for use ina machine using a sand belt. A i'iat guide supporting the sand belt enables it to work more smoothly and without concentrating wear on individual points init. A

f These and other features of the invention comprising certain details of construction and combinations of parts will be better understood from the following description of a preferred embodiment thereof shownin theI accompanying drawings in which,

if l is a front elevation of the machine;

Fig. 2 is a front elevation ofthe sand belt supporting means; 1

. Fig. 3 a side elevation thereof;

' Fig. l-

:in elevation of the righthand end of the machine;` i

a detail showing the cradle;

\ `6 is side elevation of the parts shown in Fig. 5;

Fig. 7 clamp;

Fig. S is an endelevation of the leftdiand end of the machine.

The `machine frame lOca-rries two pedestale l2 and lll at its ends in which are rotatably mounted the swing frame bed 16. This bed is preferably formed as a circular tube for reasons which will later appear. The tube contains a keyway in which is located a key lha'ving a wedge-shaped rib llprojecting from vitsoutside surface. |The bed carries a head-stock and a tail-stock i211.,` the latter ofwhich'is slidable along the bed and mayy be clamped in any position by the screw clamps 26. The main body of the tail-stock has a recess fitting over the key 18 and containing a block or gib 28 which fits over the rib 2O and may be forced :is a cross-sectionof the tail-block `inmly'down upon it by the screwBO (see.

lf T). The headstock 22 is mounted in the same way upon the bed 16, and the key 18 and blocks 28 keep the tvvo stocks rigidly in relat-ixfe position as regards rotation, though permitting the tail-stock to be dra-Wn u p lto or separated from the head-stock in oi r to lit different sizes oit Work. The tail toch carries tivo dead spindles 32 and 324 which can be screwed inand out by handles rIhis part of the mechanism is of ordinary construction and need not be `further described.. The head-stock 22 cartivo live spindles 38 and 40 Which are rivcn by elliptical gears 42, 44, respectivel \r mounted upon their outer ends.v These nears are driven by two'equival'ent ellipti-y cal gears 46, 48 Wnich are integral with ch other and rotatably mounted upon the axis of the bed 16, preferably outside of the pei; tal 12. These gears are driven by a pulley 50 integrally mounted. with respect to them. The pulley 50 is belted to a pul ley 52 on the end of a shaft '54 upon the other end ot which is a pulley 56k driven 'from a pulley 58 on the end of a shaft 60 upon the other end of which is a main receiving pulley 62 with a belt shifter 64. The shaft 54 also carries a pulley 66 which drives a pulley 68 upon a shaft 70 which drives gear mechanism of any desired type in an apron 72 causing` the apron to drive along` a rack 74 in either direction as desired, accordingl to the adjustment of the mechanism in the apron, in order to drive the carriage 7 6 to which the apron is bolted. The carriage 76 slides upon guides 7 8 and 80 in the ordinary manner and carries two arches 82 and 84. The arches are connected above by a cross-bar 86 carrying a dovetailed `guide 88 in which is adjustably mounted a slide 90 carrying the model guide' The model guide is rotatably mounted about a nearly vertical spindle 94 and carries lug 96 which is loosely confined been two set screws in ears 98 mounted npon the slide 90. The model guide is substantially flat instead of rounded, as I have found that this form produces better Work upon airplane struts which, as shown in Fig. 4. are ot elongated ovoid cross-section with two very nearly flat sides.

The bed. 76 carries'a bracket 100upon which is mounted a spindle 102 similar to the spindle 94 and carrying asand-belt .snide 104 exactly similar to the model guide Q4. but in reverse position. The sand-belt 106 passes over this 4guide and over a pulley 108 mounted upon an arm 110 whichl is a part of the bracket 100; and passes thence over pulley 112'which is mounted on one end oi a bell-crank 114 at the other end of which is a countervveight 116, the pulley 112 thus operating as a belt tightener for the sand-belt. From the belt tightener'112 the sand-belt 106 passes over a ylarge .drive pulshifted by hand when the apron mechanism is unclutched by means or' the handle 124, which operates small pinion (not shown) i'neshinp: with the raclr 7 4. The mechanism thus tar described is used as 'follows-. model 1.26 is mounted between the spindles :18 and and a rough-turned strut 19,8 is mounted between the spindles 34 and 40. The elliptical gears are so arranged with regard to the spindles that the spindles are rotated' rapidly whenV the liat sides of the strut are-in contact with the guides and are rotated slowly when the end portions of the cross-section are in Contact with the guides. This equalizes the surface speed ot the sand-belt over the work and 1 have found that the quality ot the work is improved thereby as well as that the wear on the sand-belt is madev more even and uniform. I have round also that the fiat guides worlr much better with the sand belt than curved ones, such as the Well-known model wheel, in that the action of the sand-belt made more uniform over large areas in stead of tending to cut too deeply in spots is the case when a curved guide is used. The pivoted construction enables the ,guide to follow smoothly'the changes in cross-section. of the model and work, in case they exist. I

The oscillating frame has at its right, hand end an'arm 180 towhich is pivoted a bar 132 having a notch. 134 at its rear end. .Vhen the oseillatinf;r frame is rotated clockwise in Fig. 4 to release the-work and model from their engaging instrunientalities, the notch 134 falls overa pin 186 and holds the oscillating frame with the work and model disengaged. At r`the Sametime, a lug 138 mounted on the oscillating frame swings against the laterally projecting arm of a bell-crank 140 mounted on the pedestal. 14 forcingr the baclrwardly projecting` arm thereof to the right. This backwardly projecting arm (Fig. 4) engages a lever 142, see Fig. 1, which disconnects the pulley 56 from the shaft 54, thereby shutting; off: all the power from the oscillating frame and the drive1 i .f

I have found that the action of sand-belt upon `the work it treats is radically different from that of a cutter in that unbroken trictional Contact over a large surface sets vthe strut into violent vibration. These members may be as long as ten or twelve feet and this action oi the sand-belt, especially when near their middle portions, is sometimes such as to vitiate the entire accuracy ot the operation. The action seems to be similar to that of a violin bow upon a string. l have obviated this ditliculty as follows:

A carrier 1114 is mounted upon the tube 16. It contains roller bearings 14:6 which enable it to slide freely along the tube and other roller bearings 1118 which engage the key `18 and prevent the carrier from rotating;r relatively to the tube 16. This carrier has a rib 150 which is engaged by rollers 152, one on each side, the rollers being mounted upon a bracket 1511 fastened firmly to the arch The movement o't' the carriage 76 con'u'nunicated through the arch 82 is therefore coni-- municated to the carrier 1414 which is pulled. along` with the arches, guides and sand-belt. The carrier 14st has bolted to it a ring 156 in which is rotatably mounted a ring 158 by means ot' a ball bearing` 160. This ringv carries four lingers 162, 164, 166, 168, which are pivotally mounted as at 170 upon the ring 158 upon axes which are at right angles to the axis of the ring. These fingers are all spring-pressed toward the axis ot the ringby springs 17 2 mounted in tl e ri' fr 158 and adjustable by nuts 174. Set screws 176 prevent the fingers 'trilling` too tar toward the axis 0'1 the ring. The fingers 162 and 168 are grooved shown in Fig'. (l so that they will fit the ends of the strut. 'lhe tirgers 164 and 166' have plain ends.

By the mechanism thus described, the strut is prevented 'from vibrating` under the drap; of the sand-belt, the four lingers conlinine; it resiliently but still closely and contacting' with it close to the sand-belt so that the strut is supported in all directions against vibration. I have also built machines ot the illustrated type omitting the structure shown in Figs. 5 and 6 and substituting; a model wheel of ordinary construction tor the guide 92 and a cutter head for the sand-belt to perform the so-callcd rough turning operation upon the struts. This operation leaves a spi al groove perhaps a thirty-second ot an inch deep around the strut and it is the finishing oit of the resulting ridges for which the machine illustrated in Fig. 1 is designed. A round sand-wheel is inadvisable for strut nishing' because it has less area than a belt and Wears faster, and because it has a tendency to dig and finish unevenly in spots.

Attention should be called to the structure of the oscillating trame which is the same in both machines. The weight oit this frame is largely concentrated at its center. The tube 16 in a certain machine I found to Weigh 130 pounds while the head-stock and tail-stock, which were constructed of aluminum as tar as possible,weighed about 7 5 pounds together. This concentration close to the axis makes the frame very responsive to the reaction between the model guide and the model so that it turns quickly and easily without tending to bend or distort the model and thereby vitiate the accuracy of reproduction oi' the work. lt is obvious that in cutting an object ten feet long, seven o1' eight inches wide and tivo or three inches thick, the problem oil bending the work and the model is i very serious one to overcome, and l have tound zitter much experimenting that the saving oi even a few pounds in the oscillating frame is ot supreme importance. The tubular torni oit the main member of the oscillatino` trame enables me to use minimum mass or metal for a given strength and stii'iness in the bed.

Having described my invention, what l claim as new and desire to secure by Letters Patent ot the lUnited States is 1.' 1n a machine ot the class described, two pedestals, a tube ci circular cross-section rotatably supported in the pedestals, a headstock trame mounted on the tube having` two substantially identical spind es on opposite sides ot and in the same plane with the tube, the tube being` long` as compared with the distance between the spindles, a tail-stock trame longitudinally adjustable along the tube and provided with two similarlj7 arranged spindles, mechanism 'lor rotatingv both head-stock spindles at the same speed,

and a carriage arraniged to move parallel to the tube. and carrying a model guide and a 'tool arranged on opposite sides of the tube and in similar relations to the two sets of corresponding' stocks,

2, ln a machine of the class described. a model holder and a work holder arranged 'to handle an object which is long); ascompared with its lateral dimensions, a model I.Q'nide and an abrasive belt `for treating the model and work. respectively. and a pressure plate `lfor the belt shaped like the model =guide and similarly arranged.

3. ln a machine tor turning "plane struts.` a w rk holder and a model holder. :i model guide comi'irisinp; a tlat plate, a -work guide snlistantially identical in contour with the model guide and similarly arranged with regard to its cooperatingr instrumen talities, and an abrasive belt arranged to run between thc. work guide and the work.

t. 1n a machine 'tor turning' airplane struts, a work holder and a model holder, a model snide comprisinfr a flat plate pivotally mounted upon an a i transverse to the axis ot rotation ot the model.

5. In a lathe for turning` airplane struts, model and work holdingl and rotating); means, and model and work following means the latter comprisin0,` a cradle arranged to support the work in the neighborhood olthe operating` point of the tool, and to move along' the work with the tool.

6. 1n a lathe for turning airplane struts, model and work holdingA and rotating; means, and model and work following means, the latter comprising a cradle ar- 8. ln a lathe for turning' airplane struts,

model and work holding and rotating means, and model and work lolleaving` means, the latter comprising a cradle arranged to support the worlr in all directions in the neighborhood of the operating point ot the tool, and comprising a resilient con tact member for the worlr arranged to lollow the tool along the worlr.

9. In a lathe Jfor turning airplane struts, model and work holding and rotating means, and model and work following means, the latter comprising a cradle arranged to support the worlr in all directions in the neighborhood ott the operating point of the tool, and comprising a resilient contact member for the work arranged to rotate with the work.

l0. In a lathe for turning airplane struts, model and work holding and rotating` means, and model and work following means, the latter comprising a cradle ai ranged to support the worlr in all directions in the neighborhood of the operating point of the tool and comprising a carrier, and a frame having a bearing in the carrier and arranged to encircle and support the work against vibration, and to rotate therewith in its bearing in the carrier.

1l. In a lathe for turning airplane struts, model and work holding and rotating means, and model and worlr following means, the latter comprising a cradle arranged to support the work in all directions in the neighborhood of the operating point ot the tool, and comprising a carrier, a vtrame having` a bearing in the carrier and arranged to encircle and support the worlr against vibration, and to rotate therewith in its bearing in the carrier, the frame hav,- ing resilient fingers constructed and arranged to press against the work in several directions.

l2. In a machine for making airplane struts, a swing frame consisting oi' a tube oscillatino on its axis and having a headstock and tail-stock mounted thereon, said stocks comprising model and work spindles on opposite sides ot the tube, a cradle longitudinally slidably mounted on said tube and arranged to swing with it, and constructed 'to support the work on all sides to prevent vibration, anda sand-belt arranged to treat the work in the neighborhood ot the cradle.

i3. ln a machine for forming airplane struts, a swing frame for carrying and rotating` the model and the work and variable speed gearing for rotating them at higher speed when operating upon their flat sides and at slower speed when operating upon their more sharply curved sides.

li. ln a machine ot the class described, an oscillating frame comprising a circular tube, a lrey having a wedge-shaped top mounted in a keyway on the tube, and a head-stock and tail-stock mounted on the tube for relative approach and separation, engaging the key and having a concave gib fitting over the wedge-shaped top of the lrey, means Jfor rotating the stock spindles and model and work contacting instrumentalities constructed and arranged to traverse along the tube between the stocks.

ln testimony whereof I have signed my name to this speciiication.

LELAND B. WHIPPLE. 

